Two suggestions
- After connecting via ssh, run 'screen' (sudo apt install -y screen)
That will create a virtual session. If your ssh connection breaks, that virtual session still exists.
https://linuxize.com/post/how-to-use-linux-screen/
-
Use some sort of copy command that can deal with restarting a partial copy
rsync -av /mnt/4tb/* /mnt/14tb/